There are a series of restaurants along Elm St -- from north to south something like Mojave Grille, Isabella's, Sweet Waters, Theresa's, Acquaviva (latter a block further down). I like them all except Sweet Waters.

Whereas I'd suggest you go to Cranford, to Pairings Plate + Palate (it appears fancier than it is, and it's BYO) or to Avenue East (also BYO)! I'm just not a fan of the restaurants in Westfield, but that's me...

In westfield I like the Brick Oven for a casual night. If you are looking for lunch or breakfast, there's always Turning Point. However, my favorite casual family restaurant in the area is Kilkenny Pub in Cranford. We always go when the family comes in from MA for the holidays.